Method of replacing nucleus pulposus and repairing the intervertebral disk

ABSTRACT

A process for repairing the annulus fibrosus, and replacing the nucleus pulposus. Removal of the nucleus pulposus and only as much of the annulus fibrosus and intervertebral disk as is necessary is performed. The tissue so removed is replaced by a material which is resilient, but non-dispersing upon setting. After application of the material, and after the material is set, the resiliency of the material permits motion of the vertebrae and performs the cushioning and joint functions of the intervertebral disk. The material is physiologically acceptable to the human body.

This application is a continuation-in-part of pending application Ser.No. 09/255,372, filed Feb. 22, 1999.

FIELD OF THE INVENTION

This invention relates to surgical methods generally, and is morespecifically related to a process of repairing the intervertebral diskof mammals.

BACKGROUND OF THE INVENTION

Intervertebral disks are prone to injury. Due to the low blood supply tothis area. intervertebral disks are slow to heal, and may not materiallyheal. When the annulus fibrosus is torn, or punctured, the nucleuspulposus can migrate. A ruptured/prolapsed annulus fibrosus isdemonstrated in FIG. 1. A mechanical translation of the disk material isdemonstrated in FIG. 2.

Annulus fibrosus, as referred to herein, is the marginal or peripheralportion of an intervertebral disk. The intervertebral disk is a diskwith fibrous bands surrounding the nucleus pulposus occupying the spacebetween two vertebra. The anatomy of the disk provides a cushion toallow motion, limit motion and provide space, distancing the vertebraoff the nerves and compressible tissue. Part of the vertebrae are bonyblocks, which, when stacked one upon the other, form the anteriorportion of the spine. Annulus fibrosus is also known as annulus fibrosusdisci intervertebralus. The nucleus pulposus is a substance of jellylike consistency found in the center of a intervertebral disk.

The effect of a ruptured/prolapsed annulus fibrosus may result in spasm,and neurological compromise, such as the compressed nerve indicated inFIG. 1 and other compressible soft tissues, i.e. arteries, veins.Degeneration of the condition may increase over time, resulting inchronic and debilitating pain. The condition is usually disabling.

Suppressive measures include steroidal injection, removal of the nucleuspulposus, and fusion either by donor bone, coral or by metal bracing. Ifdisk removal is performed, a healthy part of the disk is often taken,eradicating the function of the joint, and accelerating the degenerationof adjacent segments of the body, as the body attempts to stabilize.This approach frequently leaves the patient immunologically andstructurally compromised, if not permanently disabled.

Isolated treatment to only the damaged structures employing the mostnon-invasive procedure possible is preferred. This approach allows asmuch of the healthy tissue as possible to remain, and to retain normalneurological function. While the offending material can be removed, thematerial must be replaced with a material which will perform thefunction formerly performed by the material removed. A need exists for aprocess which limits the material removed from the intervertebral disk,and which replaces the material so removed with a composition that isphysiologically acceptable to the human body, and which allows theintervertebral disk to retain motion and characteristics of normal jointfunction, including cushioning the joint as compression is introducefrom the stacking of the vertebrae. The material must be pliable in itsapplication, and non-dispersing after replacement.

SUMMARY OF THE PRESENT INVENTION

The present invention is a process of repairing the disk throughreplacing the nucleus pulposus. The process of the invention desiresminimal invasiveness. Motion within the vertebrae, and joint functionand cushioning in the intervertebral disk, are regained by the process.

The process involves removal of the nucleus pulposus and only as much ofthe annulus fibrosus and intervertebral disk as is necessary. The tissueso removed is replaced by a material which is resilient andnon-dispersant upon setting, and within a temperature range of 35° and42° C. After application of the material, and after the material is set,the resiliency of the material permits motion of the vertebrae, andperforms the cushioning and joint functions of the intervertebral disk.The material is physiologically acceptable to the human body.

SUMMARY OF THE DRAWINGS

FIG. 1 shows, inter alia, a ruptured/prolapsed annulus fibrosus and theresulting migrated nucleus pulposus of an intervertebral disk.

FIG. 2 demonstrates mechanical translation of a ruptured/prolapsedannulus fibrosus.

FIG. 3 demonstrates the replacement of the nucleus pulposus and theruptured/prolapsed portion of the annulus fibrosus by the introductionof gutta percha via a mechanically facilitating device.

FIG. 4 demonstrates the intervertebral disk after repair with guttapercha.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The rupture/prolapse of the annulus fibrosus is first identified andisolated. This identification and isolation is by means such as x-ray.MRI or other diagnostic imaging procedures which are diagnosticallyacceptable. After the area of rupture/prolapse is identified andisolated, the site is surgically accessed. Since it is a goal of theinvention to minimize trauma associated with the procedure, it ispreferred to access the site through an arthroscopic procedure, ortechnology that involves minimal invasion and offense to healthy areasof the annulus fibrosus, while damaged parts of the intervertebral diskare removed. Current technology allows for surgical removal of nucleuspulposus via irrigation and suction.

The material removed is replaced with a resilient material whichphysiologically acceptable to the human body. The material is firstprepared so that it will have molten or semi-solid properties whichallow transportation of the material to the site.

In the preferred embodiment, the material used for replacement ofremoved tissue is gutta percha, Gutta percha is a geometric isomer ofnatural rubber. A substance such as mineral trioxide aggregate may beadded to the gutta percha to facilitate the binding properties, and tofacilitate healing of the affected area.

When cold, gutta percha is relatively inelastic, but as it warms, itbecomes moldable. At a high temperature, gutta percha will meltsufficiently to allow transportation of the material. Accordingly, thegutta percha is prepared by heating it to a sufficient temperature tomelt the gutta percha. The gutta percha is then injected viamechanically facilitated means into the site. FIG. 3. replacing thetissue which has been surgically removed. The gutta percha may betransported into the site by means of an applicator 2 which appliespressure and directs the material through a nozzle 8 which may utilizeinsulated properties of ceramics. Dental gutta percha is reported tocontain approximately 19-22% gutta percha, 1-4% plasticizing waxes andresins, 59-75% zinc oxide, 1-17% metal sulfates for radiopacity andtrace amounts of organic dyes for coloration.

The applicator is designed to maintain the temperature of the guttapercha above ambient temperature so that the gutta percha flows, whilealso providing pressure control, which allows the gutta percha to bedirected, and the flow volume and pressure controlled.

The gutta percha 4 replaces the nucleus pulposus and the affected area 6of the annulus fibrosus 10, and, as applicable, the intervertebral disk12. The volume of the removed tissue is replaced. Tractioning of thejoint to create a negative (relative to ambient) pressure, to facilitatespacing and flow, may be employed.

As the gutta percha cools, the gutta percha will set. At normal humanbody temperatures, the gutta percha is no longer moldable, and it is notmigratory. Accordingly, the gutta percha will remain in the site,filling the area formerly occupied by the nucleus pulposus, andrepairing the rupture/prolapsed annulus fibrosus and associated migratednucleus pulposus. The gutta percha is sufficiently resilient to restorethe partial function previously performed by the intervertebral disk ofcushioning a joint between the associated vertebrae.

If necessary, gutta percha may be subsequently removed from the site viasurgical, physical, enzymatic and/or chemical means.

What is claimed is:
 1. A process of replacing nucleus pulposus of anintervertebral disk, comprising the steps of: a. identifying a locationof a prolapse in an annulus fibrosus of an intervertebral disk; b.removing nucleus pulposus associated with the said annulus fibrosus ofsaid intervertebral disk; c. heating a resilient material which will notdisperse upon setting; and d. pressurizing the heated resilient materialand injecting the pressurized heated material through a thermallyinsulating nozzle into the intervertebral disk, such that the injectedresilient material, upon setting, will occupy a space formerly occupiedby said nucleus pulposus.
 2. The process of replacing nucleus pulposusof an intervertebral disk as described in claim 1, further comprising:removing nucleus pulposus prior to injection of said heated resilientmaterial, wherein said resilient material occupies a space formerlyoccupied by said nucleus pulposus.
 3. The process of replacing nucleuspulposus of an intervertebral disk as described in claim 2, wherein saidresilient material is a geometric isomer of natural rubber.
 4. Theprocess of replacing nucleus pulposus of an intervertebral disk asdescribed in claim 2, wherein said resilient material is a geometricisomer of natural rubber.
 5. The process of replacing nucleus pulposusof an intervertebral disk as described in claim 1, wherein saidresilient material is dental gutta percha.
 6. The process of replacingnucleus pulposus of an intervertebral disk as described in claim 2,wherein said resilient material is dental gutta percha.
 7. The processof replacing nucleus pulposus of an intervertebral disk as described inclaim 1, wherein the resilient material comprises gutta percha and zincoxide.
 8. The process for replacing nucleus pulposus of anintervertebral disk as described in claim 7, wherein the resilientmaterial comprises approximately 19 to 22% gutta percha and 59 to 75%zinc oxide.
 9. The process for replacing nucleus pulposus of anintervertebral disk as described in claim 7, wherein the resilientmaterial further comprises plasticizing waxes and resins.
 10. Theprocess of replacing nucleus pulposus of an intervertebral disk asdescribed in claim 7, wherein the resilient material further comprisesmetal sulfates.
 11. The process of replacing nucleus pulposus of anintervertebral disk as described in claim 1, wherein removal of nucleuspulposus comprises irrigation and suction.
 12. The process of replacingnucleus pulposus of an intervertebral disk as described in claim 1,further comprising: identifying the location of the pulposus withdiagnostic imaging procedures.
 13. The process of replacing nucleuspulposus of an intervertebral disk as described in claim 1, wherein theresilient material is heated to a temperature such that the resilientmaterial is moldable.
 14. A process of replacing nucleus pulposus of anintervertebral disk, comprising the steps of: a. identifying a locationof a prolapse in an annulus fibrosus of an intervertebral disk; b.removing nucleus pulposus associated with the said annulus fibrosus ofsaid intervertebral disk; c. thereafter heating to a moldabletemperature geometric isomer of natural rubber material which will notdisperse upon setting; and d. pressurizing the heated material andinjecting the pressurized heated material through a thermally insulatingnozzle into the intervertebral disk, such that the injected resilientmaterial, upon setting, will occupy a space formerly occupied by saidnucleus pulposus.
 15. The process of replacing nucleus pulposus of anintervertebral disk as described in claim 14, wherein said material isdental gutta percha.
 16. The process of replacing nucleus pulposus of anintervertebral disk as described in claim 14, wherein the materialcomprises gutta percha and zinc oxide.
 17. The process for replacingnucleus pulposus of an intervertebral disk as described in claim 16,wherein the resilient material comprises approximately 19 to 22% guttapercha and 59 to 75% zinc oxide.
 18. The process for replacing nucleusPulposus of an intervertebral disk as described in claim 16, wherein theresilient material further comprises plasticizing waxes and resins. 19.The process of replacing nucleus pulposus of an intervertebral disk asdescribed in claim 14, wherein removal of nucleus pulposus comprisesirrigation and suction.
 20. The process of replacing nucleus pulposus ofan intervebral disk as described in claim 14, further comprising:identifying the location of the pulposus with diagnostic imagingprocedures.